Download or read book Technical Summary Report for Basic Research in Thermionic Energy Conversion written by Lorin K. Hansen and published by . This book was released on 1973 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report presents the results of the past year's work in a program to investigate basic process in thermionic diodes which are important to the realization of practical thermionic energy conversion.
Download or read book Energy Conversion Program Thermionic Converter Studies written by G. L. JOHNSTON and published by . This book was released on 1962 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents: Plane-parallel thermionic converter Plasma spectroscopy experiment Glass enclosed converter Model of plasma converter operation Thermodynamic and transport properties of a cesium plasma Interaction of cesium vapor and refractory metal surface.
Download or read book Technical Summary Report for Basic Research in Thermionic Energy Conversion written by Lorin K. Hansen and published by . This book was released on 1969 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report presents the results of the past year's work in a program to investigate basic process in thermionic diodes which are important to the realization of practical thermionic energy conversion.
Download or read book Thermionics Quo Vadis written by National Research Council and published by National Academies Press. This book was released on 2002-01-18 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report evaluates the Defense Threat Reduction Agency prior and present sponsored efforts; assess the present state of the art in thermionic energy conversion systems; assess the technical challenges to the development of viable thermionic energy conversion systems for both space and terrestrial applications; and recommend a prioritized set of objectives for a future research and development program for advanced thermionic systems for space and terrestrial applications.
Download or read book Technical Summary Report for Basic Research in Thermionic Energy Conversion written by Lorin K. Hansen and published by . This book was released on 1971 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report presents the results of the past year's work in a program to investigate basic process in thermionic diodes which are important to the realization of practical thermionic energy conversion.
Download or read book Basic Research in Thermionic Energy Conversion written by Charles Warner and published by . This book was released on 1968 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: The program was directed toward an understanding of the fundamental processes occurring in thermionic energy converters and the effects of these processes on overall converter performance. A theoretical approach was studied for solving the equations which describe the wide spaced diode. In the past these equations have not been solvable with available techniques. With some reservations the new computer results agree with available experimental data. Secondly, the trapping of ions in potential wells was studied and a new criterion has been developed which relates parameters associated with double sheath emission barriers. This criterion will be useful in deciding the essential physics of converters operating below the knee of the I-V curve. (Author).
Download or read book Energy Conversion Including Magnetoaerodynamic Studies and Thermionic Converters Thermionic Converter Studies written by R. C. HORN and published by . This book was released on 1961 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt: A plane-parallel cesium thermionic converter was constructed, and is about to be put into operation. A second converter, which permits spectrographic determination of cesium species temperatures and densities, was designed. Analytical stu ies of plasma and she th phenomena occurring in high pressure operation of a converter are in progress. Elastic scat ering cross sections and momentum transfer cross sections for collisions of low energy were calculated and a report was issued. A literature survey of transition probabilities for transitions from the ground state in cesium was conducted a d a tabulation of experimental values made. (Author).
Download or read book Energy Research Abstracts written by and published by . This book was released on 1986 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Energy Conversion in the USSR Thermionic Converters written by Library of Congress. Aerospace Technology Division and published by . This book was released on 1965 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: CONTENTS: Thermoelectron emission; Volt-ampere characteristic and difference of contact potential; Positive surface ionization and evaporation heats; Space-charge and its neutralization; Transport phenomena; Qualitative theory of plasma thermoelements; Classification schemes; Vacuum with current limited by space-charge; Vacuum with space-charge compensated (Anselm's theoretical study; Rectilinear-path mode; Ioffe's concept of a plasma thermocouple; Simple diffusion mode (Moyzhes-Pikus Theoretical Study); Phenomena at increased plasma pressures; Discharge mode (Baksht-Moyzhes Theoretical Study); Arc mode.
Download or read book Thermionic Energy Conversion written by George N. Hatsopoulos and published by . This book was released on 1979-01 with total page 683 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prepared under the auspices of the U.S. Department of Energy Division of Power Systems. Volume I of Thermionic Energy Conversiondealt with processes and devices (MIT Press, 1974). Its four chapters summarized information basic to the field and not subject to substantial alteration by future developments. Volume II begins with chapter 5 and describes the scientific and engineering aspects of thermionic conversion and the experience with actual operational hardware. It summarizes the experience and analytic methods that should be useful in the development of new applications of thermionic conversion. Thermionic Energy Conversionis intended for scientists and engineers working in the field of energy conversion. With increased interest in maximizing the efficiency of present energy conversion systems, it is an important reference for scientific and engineering libraries as well. The book benefits especially from the authors' actual experience-Hatsopoulos and his firm, Thermo Electron Corporation, are leaders in this field. Gyftopoulos and his students have made basic contributions to the theory of thermionic conversion. Both authors have developed a unified quantum theory of mechanics and thermodynamics. The book covers Elements of Quantum Mechanics; Principles of Thermodynamics; Thermodynamics of Stable Equilibrium States; Thermodynamics of Steady States; Emission Phenomena; Collisionless Transport Phenomena; Analysis of Performance Characteristics of High-Pressure Diodes; Experimental Techniques; Experimental Studies and Correlations of Characteristics; Metallurgy of Electrode Materials; Design and Fabrication of Practical Convertors; and Thermionic Power System Engineering.
Download or read book Studies in Thermionic Energy Conversion written by Ragon Don Kinney and published by . This book was released on 1966 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book SECOND ANNUAL TECHNICAL SUMMARY REPORT FOR BASIC RESEARCH IN THERMIONIC ENERGY CONVERSION Covering Period November 1 1961 to October 31 1962 written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of work in a continuing program to investigate basic processes in thermionic energy conversion related to thermionic nuclear power plants for naval applications are reported. The areas in which progress is reported include statistical mechanics of Cs adsorption, space charge analysis for low pressure thermionic diodes, emission requirements for removal of space charge barriers, unignited mode of thermionic converters, interpretation of volt-ampere characteristics, vaporization and deposition at Cs-covered surfaces, and Cs purification. (auth).
Download or read book High temperature High power density Thermionic Energy Conversion for Space written by James F. Morris and published by . This book was released on 1977 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ERDA Energy Research Abstracts written by and published by . This book was released on 1977 with total page 724 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Conversion Systems Reference Handbook written by Electro-Optical Systems (Firm) and published by . This book was released on 1961 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ERDA Energy Research Abstracts written by United States. Energy Research and Development Administration and published by . This book was released on 1977 with total page 1030 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Application of Semiconductors to Thermionic Energy Converters written by Daniel C. Riley and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermionic energy conversion (TEC) is a direct heat-to-electricity conversion technology with the potential to leapfrog state-of-the-art solid-state conversion in efficiency and power density. In a thermionic energy converter, electrons evaporate from a hot electrode, the cathode, into a vacuum gap and are collected by a cooler electrode, the anode, to generate electric current. In the 1960s-1970s numerous groups reported thermionic converters with power densities above 10 W/cm^2 and conversion efficiencies of ~15%. However most of this work was tied to the US space-nuclear program which ended in 1973, and thermionics research has never fully recovered. As a result two central challenges yet remain in thermionics: (1) High operating temperatures necessary to produce electric current result in difficult materials challenges, and (2) low operating voltages due to losses associated with space charge and high anode work functions. However, new opportunities to tackle these challenges are available as a result of the breathtaking rise of semiconductor fabrication technology. In this work I present a new physical mechanism called photon enhanced thermionic emission (PETE). This concept is an improvement on thermionic emission by using light to boost the average energy of carriers in a hot p-type semiconductor cathode. Additionally, unlike in a photovoltaic cell, the waste heat from recombination losses and sub-bandgap light absorption is utilized to heat the cathode. Thus a PETE cathode can produce efficient electron emission at lower temperatures than a thermionic cathode. I will describe theoretical calculations showing that a PETE device may exceed 40% solar power conversion efficiency, and the conversion efficiency may exceed 50% if a PETE device is used in tandem with a solar thermal backing cycle. I will also describe an experimental demonstration of the PETE effect in an ultra-high vacuum photoemission measurement. In the cathode of an energy converter based on photon-enhanced thermionic emission (PETE) photoexcited carriers may need to encounter the emissive surface numerous times before having sufficient thermal energy to escape into vacuum and therefore should be confined close to the surface. However, in a traditional planar geometry, a thin cathode results in incomplete light absorption. Nanostructuring has the potential to increase light capture and boost emission by decoupling the lengths associated with photon absorption and electron emission. Nanostructures may complicate the properties of the emissive surface; therefore, the effect of nanostructuring on emission efficiency needs to be studied. In this work I describe results from a suite of simulation tools we have developed to capture the full photoemission process: photon absorption, carrier transport within the active material, and electron ballistics following emission. I show that the theoretical efficiency of a negative electron affinity emitter may be increased with nanostructures if light absorption and electron escape ballistics are considered. I then describe measurements of the photoemission efficiency of fabricated nanostructures that were designed based on the results of the simulation suite. I will also present a fundamentally new method to increase the operating voltage of a TEC by lowering the anode work function using the surface photovoltage effect. When a semiconductor surface is illuminated, photo-excited carriers form an internal dipole, or surface photovoltage (SPV), in the band-bending region and begin to flatten the bands near the surface. This SPV is analogous to the photovoltage in a photovoltaic cell and can reduce the effective work function of the material. I will describe an experimental demonstration using the SPV effect to produce a low work function surface. I will also describe a proof-of-concept demonstration of the SPV effect applied to improve the I-V characteristics of thermionic device. This generic physical process extends across materials systems and forms a realistic path to ultra-low work functions in devices to enable efficient thermionic energy conversion.
